ZyXEL Communications ADSL2+ Ethernet/USB Gateway 660RU-Tx Series, User Manual

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Prestige 660RU-Tx Series User’s Guide
Chapter 6 WAN Setup 64
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H A P T E R
6
WAN Setup
This chapter describes how to configure WAN settings.
6.1 WAN Overview
A WAN (Wide Area Network) is an outside connection to another network or the Internet.
See Chapter 3 Wizard Setup for more information on the fields in the WAN screens.
6.2 Metric
The metric represents the "cost of transmission". A router determines the best route for
transmission by choosing a path with the lowest "cost". RIP routing uses hop count as the
measurement of cost, with a minimum of "1" for directly connected networks. The number
must be between "1" and "15"; a number greater than "15" means the link is down. The
smaller the number, the lower the "cost".
The metric sets the priority for the Prestige’s routes to the Internet. If any two of the default
routes have the same metric, the Prestige uses the following pre-defined priorities:
• Normal route: designated by the ISP (see the Zero Configuration Internet Access section )
• Traffic-redirect route (see the Traffic Redirect section )
• WAN-backup route, also called dial-backup (see the Configuring WAN Backup section )
For example, if the normal route has a metric of "1" and the traffic-redirect route has a metric
of "2" and dial-backup route has a metric of "3", then the normal route acts as the primary
default route. If the normal route fails to connect to the Internet, the Prestige tries the traffic-
redirect route next. In the same manner, the Prestige uses the dial-backup route if the traffic-
redirect route also fails.
If you want the dial-backup route to take first priority over the traffic-redirect route or even the
normal route, all you need to do is set the dial-backup route’s metric to "1" and the others to
"2" (or greater).
Note: IP Policy Routing overrides the default routing behavior
and takes priority over all of the routes mentioned above (see
Chapter 28 IP Policy Routing ).